title: Associations for birthweight of twin pairs in south India.
abstract: OBJECTIVE
  The aim of this study was to determine the distribution and associations of birthweight in twin pairs among a population of pregnant women in south India.
  
  
  METHODS
  This was a retrospective case record analysis of 705 twin pair pregnancies during the period 2008-2012. Associations of birthweight with maternal age, parity, pregnancy-induced hypertension (PIH), gestational diabetes, obesity, chorionicity and sex of the twin pairs was explored using bivariate and multivariate analysis.
  
  
  RESULTS
  The median birthweight (4250 g, interquartile range 3530-4810) of dichorionic twins was significantly higher (P < 0.0001) than monochorionic twins (3880 g, interquartile range 3000-4380). Birthweight was associated with chorionicity (t = 4.04, P < 0.001), obesity (t = 2.44, P = 0.03), nulliparity (t = -2.87, P = 0.004), and PIH (t = -2.11, P = 0.04) in a multivariate linear regression model. Birthweights did not differ significantly between female-male and female-female pairs (t = 0.11, P = 0.81), female-male and male-male pairs (t = -0.62, P = 0.54) or female-female and male-male pairs (t = -0.78, P = 0.43) in a multivariate linear regression model. The highest birthweight of the twin pair did not differ significantly (t = 1.27, P = 0.21) by sex of the twin.
  
  
  CONCLUSIONS
  Birthweight of twins was significantly associated with chorionicity, obesity, PIH and nulliparity in this population. A potential masculinization effect was not found as the total birthweights did not differ significantly by sex of the twin pairs.
authors.affiliation: Fellow Diplomate National Board, High Risk Pregnancy, Fernandez Hospital, Hyderabad, India.
authors.forename: Arati
authors.initials: A
authors.lastname: Singh
authors.forename: Anupama
authors.initials: A
authors.lastname: Singh
authors.forename: Praveen K
authors.initials: PK
authors.lastname: Nirmalan
mesh_terms: D001724:Birth Weight; D015992:Body Mass Index; D004200:Diseases in Twins / Q000453:epidemiology / Q000209:etiology*; D005260:Female; D005317:Fetal Growth Retardation / Q000453:epidemiology / Q000209:etiology*; D005320:Fetal Macrosomia / Q000453:epidemiology / Q000209:etiology*; D006801:Humans; D046110:Hypertension, Pregnancy-Induced / Q000503:physiopathology*; D007194:India / Q000453:epidemiology; D007231:Infant, Newborn; D008297:Male; D009765:Obesity / Q000503:physiopathology*; D010298:Parity; D011247:Pregnancy; D059285:Pregnancy, Twin; D039401:Prenatal Nutritional Physiological Phenomena; D012189:Retrospective Studies; D014429:Twins, Dizygotic
keywords: birthweight; chorionicity; sex; twin pregnancy